1. Field of the Invention
The invention relates to a Printed circuit card for a personal computer comprising a main board and at least one modular board which is connectible to the main board and which has at least one ROM in which identification is stored.
2. Description of Related Art
PC-cards, particularly user boards, are connected by contact terminals to a control means which is generally a personal computer. It is to be understood that user board 11 refers to is a hardware system with which a user can test and determine the hardware mounted on the user board, particularly the integrated circuits. Also, the user boards also considerably facilitate the development of one's own hardware and software. User boards are thus especially suited for evaluating integrated circuits.
Particularly with complex integrated circuits, it is important to first offer the user effective and user-friendly technical assistance for learning the new, complex integrated circuits, for example, ISDN modules (Integrated Services Digital Network). This is possible with the assistance of user boards. A trend toward PC-assisted boards has occurred with the increased use of personal computers (PC). The crux of such PC-assisted user boards is thus a circuit arrangement, which is referred to as a PC-card arranged on a motherboard and such PC card is plugged into a terminal strip provided in the personal computer.
PC-assisted user boards previously disclosed are composed of a PC-card which can either not be functionally expanded or adapted at all (see, for example, Electronic Design, Dec. 10, 1987, pages 85 through 88; Communications Engineering International, October 1987, pages 65 through 71; and AMD Product Information; ISDN Evaluations Tools and System Software) or that can only be functionally expanded or adapted on the basis of further pluggable cards in what is referred to as sandwich structures.
In every modularly constructed PC-card such as, for example, those in sandwich structure, it is fundamentally necessary to inform the control device of what modules the PC-card is composed. When the PC-card is composed of a main board that is application-independent and is needed for communication with the control device and to which module boards associated to the respective application are connected, then the information regarding which module boards are connected to the main board must be available to the control device.
A simple but undesirable possibility comprises providing the module board with manually actuatable switches, for example DIL switches (dual in-line switches) which can be interrogated by the control device. Of course, hard-wired bridges can also be provided instead of such switches. This undesirable solution has the additional disadvantage that maladjustments are difficult to recognize.
Another possibility of identifying the module board is to have the user to enter into a dialogue with the control device, with generally a picture screen dialogue, which informs the control device which module board is presently connected to the main board. It is especially disadvantageous in this procedure, however, for the user to be forced to correctly input a great deal of information into the control device. A simple identification of the module board does not occur with this possible solution.
A third possibility for identification of the module board is to in define a module identification code with hardwired bridges on the individual module boards. After what is referred to as a "power on" reset, the identification code of the module board which is connected to the main board is interrogated by the control device. This identified identification code serves the purpose of depositing an image of the current module configuration into the memory of the control device from a collection of module description tables that, for example, can be deposited on a diskette. The disadvantage of this solution is that it is not fully automatic as seen from the viewpoint of the user. The user must always see to it that his collection of module description tables coincides with the module boards he uses. Moreover, he must update his collection of module description tables with the description table for a new module for every new module board which is to be employed.